[android-components](../../index.md) / [org.mozilla.telemetry.event](../index.md) / [TelemetryEvent](index.md) / [extra](./extra.md)

# extra

`open fun extra(key: `[`String`](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)`, value: `[`String`](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-string/index.html)`): `[`TelemetryEvent`](index.md) [(source)](https://github.com/mozilla-mobile/android-components/blob/master/components/service/telemetry/src/main/java/org/mozilla/telemetry/event/TelemetryEvent.java#L106)